Carrick is a tremendous player with one flaw that really has stopped him being able to considered as top class - that's his inability to handle a pressing game for a sustained period. It's not to say he can't but, he needs help when pressed - when he has people moving and providing options but, if that's not available then he folds. Nothing to be ashamed of as few but, the true greats are able to deal with it.
Getting to the point - I think with the current squad, with likes of Blind, Herrera, ADM - he'll have options, if pressed he will not be forced to fold and because of that everything else he brings in terms of reading the game, controlling the pace, his passing and experience will I think be truly welcome stabilizing presence. Definitely be interesting to see if LVG uses him and Blind together because for some reason I think Blind was bought primarily due to how long Carrick was going to be out and LVG had planned to use him in the role Blind plays now. If he plays both then we lose one of our more attacking players but, that might not be a bad thing to add more confidence in the back.